Plasma membrane is composed of the phospholipid bilayer with hydrophilic heads on the outside and hydrophobic tails on the inside. Cholesterol is bound between the phospholipids. Glycolipids, lipids with carbohydrates attached, and glycoproteins, proteins with carbohydrates attached, are bound to the extracellular side. Cytoskeletal filaments are bound to the intracellular side. There are transmembrane protein channels and integral membrane proteins and peripheral membrane proteins within the plasma membrane.